Selective antagonists of A2B adenosine receptors

ABSTRACT

A compound of the following formula:wherein R is an aliphatic or cycloaliphatic amine group or a pharmaceutically acceptable salt thereof and a pharmaceutically acceptable salt thereof. The compounds of formula (I) may be used to treat, among other indications, asthma and diarrhea.

This application claims the benefit of Provisional application No.60/151,649, filed Aug. 31, 1999.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

The present invention was made with the assistance of US Governmentfunding (NIH Grant R29HL55596, N1H 1 PO1 HL56693). The US Government mayhave some rights in this invention.

FIELD OF THE INVENTION

The present invention relates to novel pharmaceutical compounds usefulas selective antagonists of the A_(2B) adenosine receptor. Furthermore,the present invention relates to novel pharmaceutical compositionsuseful for treating certain indications including asthma and diarrhea.The present invention also relates to novel methods of treating certainindications including asthma and diarrhea.

BACKGROUND OF THE INVENTION

There is substantial evidence that adenosine modulates manyphysiological processes. Its actions are mediated by interaction withspecific cell membrane receptors. Four types of adenosine receptors havebeen identified: A₁, A_(2A), A_(2B) and A₃. All four subtypes have beencloned from human tissue. Adenosine receptors have the seventransmembrane domain structure typical of G protein-coupled receptors.Adenosine receptors are widely distributed throughout the body and areprobably present in every cell.

Adenosine receptors were initially classified by the ability to inhibit(A₁) or activate (A₂ and A_(2B)) adenylate cyclase. A₃ receptors alsoinhibit adenylate cyclase. Modulation of adenylate cyclase is mediatedthrough coupling to G_(s) and G_(i) guanine-nucleotide regulatoryproteins. It is now known that adenosine receptors are also coupled toother intracellular signaling pathways. A₁ and A₃ receptors, forexample, can couple to phospholipase C; A₁ receptors are also coupled toK channels. A_(2B) receptors are also coupled to Gq and mediateactivation of PLC, Ras and MAP kinases.

Substituted xanthines represent the most potent class ofadenosine-receptor antagonists reported to date. See Katsushima et al.,Structure-Activity Relationships of 8-cycloalkyl-1,3-dipropylxanthinesas Antagonists of Adenosine Receptors, J. Med. Chem., 33:1906-1910(1990); and Martinson et al., Potent Adenosine Receptor Antagonists thatare Selective for the A₁ Receptor Subtype, Molecular Pharmacology,31:247-252 (1987).

The study of A_(2B) receptors has been hampered by the lack of selectivepharmacological probes. Nonetheless, A_(2B) receptors can bedistinguished from A_(2A) receptors by their low affinity and theirdistinct rank order of potency for agonists. NECA(5′-N-ethylcarboxamidoadenosine) is one of the most potent agonist atA_(2B) receptors, but is also effective at A_(2A) receptors. On theother hand, the agonist CGS 21680(4-((N-ethyl-5′carbamoyladenos-2-yl)-aminoethyl)-phenylpropionic acid)is virtually inactive at A_(2B) receptors, whereas it is as potent asNECA at A_(2A) receptors. The lack of effectiveness of CGS 21680 hasproven useful in the functional characterization of A_(2B) receptors.A_(2B) receptors also have a very low affinity to the A₃ selectiveagonists IB-MECA and N⁶-benzyl NECA. These agonists can, therefore, beused to differentiate between A_(2B) and A₃ receptors. In summary,A_(2B) receptors can be identified by their unique rank order of potencyfor agonists NECA>PIA≧IB-MECA>CGS-21680.

Whereas A_(2B) receptors have, in general, a lower affinity for agonistscompared to other receptors subtypes, this is not true for antagonists.The structure activity relationship of adenosine antagonists on A_(2B)receptors has not been fully characterized, but at least some xanthinesare as or more potent antagonists of A_(2B) receptor subtypes than ofother subtypes. In particular, DPSPX(1,3-dipropyl-8-sulphophenylxanthine), DPCPX and DPX (1,3diethyl-phenylxanthine) have affinities in the mid to high nM range.

The present inventors have recognized that A_(2B) receptors modulateimportant physiological processes. As stated by Feoktistov et al.,Adenosine A_(2B) Receptors as Therapeutic Targets, Drug Dev Res 45:198;A_(2B) receptors have been implicated in mast cell activation, asthma,vasodialation, regulation of cell growth, intestinal function, andmodulation of neurosecretion. Also see Feoktistov et al. TrendsPharmacol Sci 19:148-153.

Methods of mast cell activation, treating and/or preventing asthma andvasodialation, regulation of cell growth and intestinal function, andmodulation of neurosecretion are all objects of the present invention.

As stated above, A_(2B) receptors modulate important physiologicalprocesses. For example, A_(2B) receptors are found in the colon in thebasolateral domains of intestinal epithelial cells, and increasechloride secretion. Selective A_(2B) antagonists with poorgastrointestinal absorption can also be useful in blocking intestinalchloride secretion. Thus, it is an object of the present invention toprevent and/or treat inflammatory gastrointestinal tract disordersincluding diarrhea.

Additionally, there are vascular beds in which NECA produces profoundvasodilation. Based on reasonable confirmation that A_(2B) receptorsmediate vasodilation in the pulmonary circulation, an object of thepresent invention is to prevent and/or treat cardiac diseases.

A_(2B) receptors are also present in cultured vascular smooth musclecells and have been found to inhibit their growth. Since impairedadenosine mechanisms may play a role in the vascular remodeling processobserved in atherosclerosis and hypertension, an object of the presentinvention is to prevent and/or treat atherosclerosis and hypertension.

A_(2B) receptors are also present in endothelial cells and have beenfound to stimulate their growth. Since this will lead to growth of newblood vessels (angiogenesis). An object of this invention is to preventand/or treat diseases characterized by abnormal blood vessel growth,such as diabetic retinopathy and cancer.

There is evidence that A_(2B) receptors modulate mast cell function andthat A_(2B) receptors are present in mouse bone marrow-derived mastcells. A_(2B) receptors have been shown to produce direct activation ofHMC-1 cells, a cell line with phenotypic characteristics of human lungmast cells. This process involved activation of PLC through Gq proteins,and activation of MAP kinasis, intracellular processes not previouslydescribed for A₂ receptors. Virtually identical findings have beenreported in a dog mastocytoma cells line. Evidence based on the researchof the present inventors, using immunofluorescence techniques with aspecific chicken anti-human A_(2B) antibody, indicates the presence ofA_(2B) receptors in human lung mast cells obtained from asthmatics bybronchoalveolar lavage cells. Thus, an object of the present inventionis to prevent and/or treat asthma. Asthma continues to be a substantialmedical problem that affects approximately 5-7% of the population.Despite advances in its treatment, the prevalence of asthma emergencydepartment visits, hospitalizations, and mortality related to thedisease, all appear to be on the rise.

Additionally adenosine treatments such as inhaled adenosine provokesbronchoconstriction in asthmatics, but not in normals. This processinvolves mast cell activation because it is associated with the releaseof mast cell mediators, including histamine, PGD2-β-hexosaminidase andtryptase, and because it can be blocked by specific histamine H₁blockers and chromolyn sodium. Furthermore, adenosine has been shown topotentiate activation of purified human lung mast cells. The lowaffinity of this process suggests the involvement of A_(2B) receptors.Given that inhaled adenosine has no effect in normals, there appears tobe an intrinsic difference in the way adenosine interacts with mastcells from asthmatics. The in vitro response produced by A_(2B)receptors in HMC-1 cells and in dog mastocytoma cells appears to mimicin vivo responses to inhaled adenosine in asthmatics, inasmuch asadenosine provokes mast cells activation in these cell lines as it doesin asthmatics. Thus, an object of the present invention is a method ofmodulating mast cell function or activation of human lung cells.

Theophylline remains an effective antiasthmatic agent even though it isa poor adenosine receptor antagonist. However, considerable plasmalevels are needed for it to be effective. Additionally, Theophyllinealso has substantial side effects, most of which are due to its CNSaction, which provide no beneficial effects in asthma, and to the factthat it non-specifically blocks all adenosine receptor subtypes. Theside effect profile of theophylline, therefore, can be improvedsubstantially by generating selective and potent A_(2B) antagonists suchas the compounds of the present invention.

It is known that adenosine exhibits neurotransmitter depressingactivity, bronchospasmic activity, bone absorption promoting activity,and the like via an A₂ receptor. Therefore, adenosine A₂ receptorantagonists are expected as therapeutic agents for various kinds ofdiseases caused by hyperergasia of adenosine A₂ receptors, for example,therapeutic agents for Parkinson's disease, anti-dementia agents,antidepressants, anti-asthmatic agents, and therapeutic agents forosteoporosis. Thus, an object of the present invention is providing sucha therapeutic agent.

U.S. Pat. Nos. 4,352,956 and 4,804,664 to Kjellin et al. disclose theantiasthmatic drug enprofylline. Enprofylline has been discovered to bea relatively selective A_(2B) antagonists. Enprofylline is of thefollowing formula:

As is more fully described below, the compounds of the present inventionhave a potency much higher than enprofylline and are yet 40- to 60-foldselective compared to A_(2A) and A₁.

DESCRIPTION OF THE PRIOR ART

As stated above, U.S. Pat. Nos. 4,325,956 and 4,804,664 to Kjellin etal. disclose xanthine derivatives including enprofylline used for thetreatment of cardiac disease and chronic obstructive airway disease.

U.S. Pat. No. 4,089,959 to Diamond discloses xanthine derivatives usefulfor treating bronchial asthma and other bronchospastic diseases. Morespecifically, the xanthine derivatives 1,3,8-trialkylxanthines. Diamonddiscloses that the introduction of an alkyl group in the 8-position ofthe xanthine nucleus has been discovered to produce a compound havinglong lasting activity.

U.S. Pat. No. 4,120,947 to Diamond discloses1,3-dialkyl-7-carbomethoxytheophylline xanthine derivatives useful intreating bronchospastic and allergic diseases. U.S. Pat. No. 4,120,947discloses examples where xanthine derivatives with the carbomethoxysubstituent at the 7-position shows greater activity than theophylline.

U.S. Pat. No. 5,641,784 to Kufner-Muel et al. discloses 1,3-dialkylxanthine derivatives that may comprise an N-linked saturated 5- or6-membered ring which may optionally contain oxygen or sulfur as afurther heteroatom. The xanthine compounds are disclosed as being usefulfor the symptomatic therapy of degenerative disorders of the centralnervous system such as, for example, senile dementia and Alzheimer'sdisease, Parkinson's disease, and traumatic brain injury.

U.S. Pat. No. 4,696,932 to Jacobson et al. discloses xanthinederivatives characterized by the presence of lower alkyl groups such asn-propyl groups at the 1 and 3 position on the theophylline ring and bya variety of para-substituents on a 8-phenyl ring. The compounds aredisclosed as having significant activity as antiallergenic andantiasthmatic drugs as well as being useful in the treatment of cardiacand renal failure, high blood pressure, and depression.

Jacobson et al., Drug Rev Res 47:45-53 (1999) discloses 8-alkyl or8-cycloalkyl xanthine derivatives that are described as beingantagonists of A_(2B) adenosine receptors. Jacobson et al. furtherdisclose that the A_(2B) AR subtype has been found to be involved in thecontrol of cell growth and gene expression, vasodilatation, and fluidsecretion from intestinal epithelia.

U.S. Pat. No. 5,877,180 to Linden et al. discloses xanthine derivativeantagonists of A₂ adenosine receptors as being effective for thetreatment of inflammatory diseases. Linden et al. further disclose thatexamples of the inflammatory diseases that may be treated according toU.S. Pat. No. 5,877,180 include ischemia, arthritis, asthma, multiplesclerosis, sepsis, septic shock, endotoxic shock, gram negative shock,toxic shock, hemorrhagic shock, adult respiratory distress syndrome,TNF-enhanced HIV replication and TNF inhibition of AZT and DDI activity,organ transplant rejection (including bone marrow, kidney, liver, lung,heart, skin rejection), cachexia secondary to cancer, HIV, and otherinfections, osteoporosis, infertility from endometriosis, cerebralmalaria, bacterial meningitis, adverse effects from amphotericin Btreatment, adverse effects from interleukin-2 treatment, adverse effectsfrom OKT3 treatment, and adverse effects from GM-CSF treatment.

U.S. Pat. Nos. 5,670,498 and 5,703,085 to Suzuki et al., disclosesxanthine derivative A₂ receptor antagonists useful as therapeutic agentsfor various kinds of diseases caused by hyperergasia of adenosine A₂receptors, for example, therapeutic agents for Parkinson's disease,anti-dementia agents, anti-depressants, anti-asthmatic agents andtherapeutic agents for osteoporosis.

U.S. Pat. No. 5,516,894 to Reppert discloses A_(2B) antagonists that areuseful as therapeutics to reduce inflammatory gastrointestinal tractdiseases or asthma.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a method for inhibitingactivation of the A_(2B) receptor by treating the receptor with acompound of the formula:

wherein R is an aliphatic or cycloaliphatic amine group. Preferably R isa C₁ to C₆ alkyl amine group, C₁ to C₆ dialkyl amine group, piperidinogroup, piperazino group, pyrrolino group, pyrrolidino group, amorpholino group, or an amino cyclohexyl derivative. More preferably,

R is pyrrolidino as shown in the following formula:

It is another object of the present invention to provide a method ofpreventing and/or treating asthma, bronchospastic and allergic diseasesas well as other obstructive airway-type diseases comprisingadministering a compound of the above-described formula (I). It is afurther object of the present invention to provide a method forpreventing and/or treating cardiac disease and Parkinson's diseasecomprising administering a compound of formula (I).

Other objects of the present invention include a method of antagonizingA_(2B) receptors comprising administering to a mammal in need thereof aneffective amount of a compound of formula (I); a method of treatingasthma comprising administering to a mammal in need thereof an effectiveamount of a compound of claim 1; method of treating diarrhea comprisingadministering to a mammal in need thereof an effective amount of acompound of formula (I).

Furthermore, the present invention discloses a method of regulating atleast one of smooth muscle tone, cell growth, intestinal function, andneurosecretion.

Another object of the present invention is to provide a method oftreating inflammatory gastrointestinal tract disorders comprisingadministering to a mammal in need thereof an effective amount of acompound of formula (I).

Another object of the present invention is to provide for a method oftreating Alzheimer's disease, Parkinson's disease, dementia, depression,or traumatic brain injury comprising administering to a mammal in needthereof an effective amount of compound of formula (I).

Another object of the present invention is to provide a method oftreating inflammatory diseases comprising administering to a mammal inneed thereof an effective amount of a compound of formula (I). Theinflammatory diseases include asthma, multiple sclerosis, sepsis, septicshock, endotoxic shock, gram negative shock, toxic shock, hemorrhagicshock, adult respiratory disease syndrome, TNF-enhanced HIV replication,TNF inhibition of AZT and DDI activity, organ transplant rejection,cachexia secondary to cancer, HIV, osteoporosis, infertility fromendometriosis, cerebral malaria, bacterial meningitis, adverse effectsfrom amphotericin B treatment, adverse effects from interleukin-2treatment, adverse effects from OKT3 treatment, and adverse effects fromGM-CSF treatment.

The administration of a compound of formula (I) may be, for example, byoral, parenteral, or by inhalation mans in the form of tablets,capsules, solutions, elixirs, emulsions, aerosols, and the like. Typicaleffective doses in humans may range from, for example, from 0.2 to 10milligrams per kilogram of body weight, preferably from 0.4 to 5milligrams per kilogram, more preferably from 0.6 to 2 milligrams perkilogram, depending on the route of administration. However, theeffective dose can be determined by one of ordinary skill in the artwithout undue experimentation.

DESCRIPTION OF THE DRAWING

FIG. 1: A graph showing the antagonistic effects of xanthine derivativeson A_(2B) receptors. A Schild analysis derived from dose-response curvesfor accumulation of cAMP produced by NECA in human erythroleukemia cellsin the absence and in the presence of increasing concentrations of theantagonists. Schild analysis revealed a liner relationship for allcompounds, suggesting competitive antagonism at A_(2B) receptors. Theintercept at the x-axis is an estimate of the Ki of the antagonists. Theplot compares DPSPX, enprofylline, theophylline, and a compound offormula (II) of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides for a novel compound of the followingformula:

wherein R is an aliphatic or cycloaliphatic amine group. Preferably R isC₁ to C₆ alkyl amine group, C₁ to C₆ dialkyl amine group, piperidinogroup, piperazino group, pyrrolino group, pyrrolidino group, or amorpholino group, or an amino cycloxexyl derivative. Preferably the Rgroup is bonded to the xanthine core at the nitrogen atom of the Rgroup. Preferably the aliphatic or cycloaliphatic amine R group is asecondary amine group. More preferably, R is pyrrolidino as shown in thefollowing formula:

The present invention further provides for a compound of formula (I) ora pharmaceutically acceptable salt thereof being administered as part ofa method of preventing and/or treating asthma. An additional embodimentof the present invention provides for a compound of formula (I) or apharmaceutically acceptable salt thereof being administered as part of amethod of preventing and/or treating diarrhea. Additional embodiments ofthe present invention include compound (I) or a pharmaceuticallyacceptable salt thereof being administered as part of a method ofregulating smooth muscle tone, cell growth, intestinal function andneorosecretion.

Another embodiment of the present invention is to provide compounds (orpharmaceutically acceptable salts thereof or compositions that areuseful as therapeutic agents for the various kinds of diseases caused byhyperergasia of adenosine A₂ receptors listed in U.S. Pat. No. 5,670,498to Suzuki et al. such as, for example, Parkinson's disease, dementia,depression and osteoporosis.

For the purposes of this disclosure, a compound of formula (I) isunderstood to include the pharmaceutically acceptable salt(s) thereof.The pharmaceutically acceptable salts of a compound of formula (I)include, for example, pharmaceutically acceptable acid additional salts,metal salts, ammonium salts, organic amine addition salts, amino acidaddition salts.

Preferred pharmaceutically acceptable acid addition salts include saltsof mineral acids, for example, hydrochloric acid, sulfuric acid, nitricacid, and the like; salts of monobasic carboxylic acids, such as, forexample, acetic acid, propionic acid, and the like; salts of dibasiccarboxylic acids, such as maleic acid, fumaric acid, oxalic acid, andthe like; and salts to tribasic carboxylic acids, such as,carboxysuccinic acid, citric acid, and the like. Further examples of thepharmaceutically acceptable salts that may be used as forms of acompound of formula (I) of the present invention includes thosedisclosed in U.S. Pat. No. 5,870,180 to Linden et al.; U.S. Pat. No.5,780,481 to Jacobsen et al.; U.S. Pat. No. 4,325,956 to Kjellin et al.;and U.S. Pat. No. 5,670,498 to Suzuki et al.

In the methods of the present invention, the A_(2B) adenosine receptorantagonists herein described form the active ingredient, and aretypically administered in an admixture with suitable pharmaceuticaldiluents, excipients or carriers (collectively referred to as “carrier”materials) suitably selected with respect to the intended form ofadministration (i.e., oral tablets, capsules, inhalers, syrups, etc.),and consistent with conventional pharmaceutical practices.

A compound of formula (I) may be prepared as follows: A1-H-3-isobutylxanthine compound is used as a starting material (see K.R. H. Wooldrige and R. Slack, J Chem. Soc., 1863 (1962)). The1-H-3-isobutylxanthine compound is brominated as described for thepreparation of 1-methyl-3-isobutyl-8-bromoxanthine (see G. L. Kramer, J.E. Garst, and J. N. Wells, Biochemistry, 16:3316 (1977)). Compounds offormula (I) are prepared by reaction of 1-H-3-isobutylxanthine with thecorresponding secondary amine (i.e., the R group of formula (I)), asdescribed for the preparation of 1,3-dipropyl-8-pyrrolidinoxanthine (seeT. Katsushima, L. Nieves, and J. N. Wells, J.Med. Chem. 33:1906-1910(1990)).

In clinical practice, the compounds and compositions of the presentinvention will normally be administered orally, rectally, nasally,sublingually, by injection or by inhalation.

For example, compounds of formula (I) and/or pharmaceutically acceptablesalts thereof can be administered as they are, or in the form of variouspharmaceutical compositions. The pharmaceutical compositions inaccordance with the present invention can be prepared by uniformlymixing an effective amount of a compound of formula (I) and/or apharmaceutically acceptable salt thereof, as an active ingredient, witha pharmaceutically acceptable carrier. If oral administration isdesired, for example, preferably such pharmaceutical compositions areprepared in a unit dose form suitable for oral administration.

For preparing a pharmaceutical composition of the present invention fororal administration, any useful pharmaceutically acceptable carrier canbe used. That is, the particular pharmaceutically acceptable carrier isnot known to be critical. In fact, the only limitation as to thematerials used in preparing the compositions of the present invention usthat the materials should be pharmaceutical pure and non-toxic in theamounts used. For example, liquid preparations for oral administrationsuch as suspension and syrup can be prepared using water, sugars such assucrose, sorbitol, and fructose, glycols such as polyethylene glycol andpropylene glycol, oils such as sesame oil, olive oil, and soybean oil,preservations such as p-hydroxybenzoates, flavors such strawberry flavorand peppermint, and the like. Powders, pills, capsules, and tablets canbe prepared using excipients such as lactose, glucose, sucrose, andmannitol, disintegrating agents such as starch and sodium alginate,lubricants such as magnesium stearate and talc, binders such aspolyvinyl alcohol, hydroxypropyl cellulose, and gelatin, surfactantssuch as fatty acid esters, plasticizers such as glycerin, and the like.Tablets and capsules may be the most useful oral unit dose forms becauseof the readiness of administration. For preparing tablets and capsules,solid pharmaceutical carriers are preferably used.

The compounds of formula (I) can be administered orally, for example,with an inert diluent with an edible carrier. They can be enclosed ingelatin capsules or compressed into tablets. For the purpose of oraltherapeutic administration, the compounds can be incorporated withexcipients and used in the form of tablets, troches, capsules, elixirs,suspensions, syrups, waters, chewing gums, and the like. Thesepreparations should preferably contain at least 0.5% by weight of acompound of formula (I), but may be varied between about 0.05% to about10%, more preferably between 0.1% and about 5% by weight, depending uponthe particular form. The amount of the compound of formula (I) in suchcompositions is such that a suitable dosage will be obtained.

Tablets, pills, capsules, troches, and the like may further comprise thefollowing ingredients: a binder, such as micro-crystalline cellulose,gum tragacanth or gelatin; an excipient, such as starch or lactose; adisintegrating agent, such as alginic acid, Primogel, corn starch, andthe like; a lubricant, such as magnesium stearate or Sterotes; aglidant, such as colloidal silicon dioxide; a sweetening agent, such assucrose, saccharin or aspartame; or flavoring agent, such as peppermint,methyl salicylate, or flavoring such as orange flavoring. When thedosage unit form is a capsule it may further comprise, in addition tothe compound of formula (I), a liquid carrier, such as a fatty oil.

Other dosage unit forms can further comprise other materials that modifythe physical form of the dosage unit, for example, as coatings. Thus,tablets or pills can be coated with sugar, shellac, or other entericcoating agents. A syrup may contain, in addition to the activecompounds, sucrose as a sweetening agent and preservatives, dyes,colorings and flavors. For purposes of parenteral therapeuticadministration, the compounds of formula (I) can be incorporated into asolution or suspension. These preparations should preferably contain atleast 0.05% of the aforesaid compound, but may be varied between 0.01%and 0.4%, more preferably between 0.8 % and 0.1 % of the weight thereof.The amount of active compound in such compositions is such that asuitable dosage will be obtained.

Injectable preparations can be prepared using a carrier such asdistilled water, a salt solution, a glucose solution or a mixture of asalt solution, suspension, or dispersion according to a conventionalmethod by using a suitable solubilizing agent or suspending agent.Solutions or suspensions of the compound of formula (I) can also includethe following components: a sterile diluent, such as water forinjection, saline solution, fixed oils, polyethylene glycols, glycerine,propylene glycol or other synthetic solvents: antibacterial agents, suchas benzyl alcohol or methyl parabens; antioxidants, such as ascorbicacid or sodium bisulfite; chelating and agents, such asethylenediaminetetraacetic acid; buffers such as acetates, citrates orphosphates; and agents for the adjustment of tonicity, such as sodiumchloride or dextrose. The parenteral preparation can be enclosed inampoules, disposable syringes or multiple dose vials made of glass orplastic.

Compounds of formula (I) may also be administered by inhalation in theform of aerosol, fine powder, or spray solution. In the case of aerosoladministration, the compound of the present invention is dissolved in anappropriate pharmaceutically acceptable solvent such as, for example,ethyl alcohol or a combination of miscible solvents, and the resultingsolution is mixed with a pharmaceutically acceptable propellant.Commercially available nebulizers for liquid formulations, including jetnebulizers and ultrasonic nebulizers are useful for such administration.Liquid formulations can be directly nebulized and lyophilized powder canbe nebulized after reconstitution. For administration by inhalation, theantagonists are conveniently delivered in the form of an aerosol spraypresentation from pressurized packs or nebulizers. The compounds mayalso be delivered as powders which may be formulated and the powdercomposition may be inhaled with the aid of an insufflation powderinhaler device.

The effective dose and the administration schedule vary depending uponthe mode of administration, the age, body weight, and conditions of apatient, etc. However, generally, compounds of formula (I) or apharmaceutically acceptable salt thereof is administered in a daily doseof 6 to 800 mg, preferably from 12 to about 400 mg, and more preferablyfrom 18 to 160 mg.

Other features of the invention will become apparent in the course ofthe following examples which are given for illustration of the inventionand are not intended to be limiting thereof.

EXAMPLE 1

This Example illustrates how the compounds of the invention may beincorporated in pharmaceutical compositions.

Aerosol for Inhalation Active substance 1.50 g “Miglyol” (RegisteredTrade Mark) 0.02 g “Frigen” (Registered Trade Mark) ad 100.0 g11/12/13/114 “Frigen” is used to denote the halogenated hydrocarbons.“Frigen” 114 is 1,2-dichloro-1,1,2,2-tetrafluorethane, “Frigen” 113 is1,1-difluoro-2,2-dichlorotrifluorotrichlorethane, “Frigen” 11 istrichloromonofluoromethane and “Frigen” 12 is dichlorodifluoromethane.“Miglyol” denotes a triglyceride of saturated vegetable oils. Or apulver aerosol where the active substance is mixed with lactose.

Tablets Active substance 20.0 mg Maize starch 25.0 mg Lactose 190.0 mgGelatin 1.5 mg Talc 12.0 mg Magnesium stearate 1.5 mg 350. mg

Suppositories Active Substance 50.0 mg Ascorbyl palmitate 1.0 mgSuppository base (Imhausen H) ad 2000.0 mg

Injection Solution Active substance 2.000 mg Sodium hydroxide 0.310 mgSodium purosulphite 0.500 mg Disodium edetate 0.100 mg Sodium chloride8.500 mg Sterile water for injection ad 1.00 g

EXAMPLE 2

This example compares the potency and selectivity towards variousadenosine receptors of a compound of formula (I) wherein R ispyrrolidino to the potency and selectivity of theophylline, DPSPX(1,3-dipropyl-8-p-sulfophenylxanthine), and enprofylline.

Antagonist potency (K₁ or K_(B), μM) A₁ A_(2A) A_(2B) A₃ CompoundReceptor Receptor Receptor Receptor Theophylline 8.5¹ (r) 25² (r) 5³ (h)>100⁹ (r) DPSPX 0.14¹ (r) 0.79² (r) 0.14³ (h) >100⁹ (r) Enprofylline156⁴ (h) 32⁵ (h) 7^(3.6) (h) 56¹⁰ (h) Formula (I) 31⁷ (h) 20⁸ (h) 0.525³(h) 53¹¹ (h) ¹Displacement of [³H] PIA binding from rat brain membranes.(See A. S. Rovena et al. Drug Dev. Res. 39: 243-252 (1996) and Ukena etal. Febs Letters 209: 122-128 (1986)). ²Displacement of [³] CGS 21680from rat striatal membranes. (See I. Hide et al. Mol. Pharmacol. 41:352-359 (1992)). ³Inhibition of NECA-stimulated cAMP in HEL cells. (SeeI. Feoktistov and I. Biaggioni. Mol. Pharmacol. 43: 909-914 (1993)).⁴Displacement of [³H] DPCPX from membranes of HEK-293 cells transfectedwith human A₁. (See J. Linden et al. Life Science. 62: 1519-1524(1998)). ⁵Displacement of [³H] CGS 21680 from membranes of HEK-293 cellstransfected with human A_(2A). (See A. S. Rovena et al. Drug Dev. Res.39: 243-252 (1996)). ⁶Displacement of [³H] 1,3-diethyl-8-phenylxanthinefrom membranes of HEK-293 cells transfected with human A_(2A). (See A.S. Rovena et al. Drug Dev. Res. 39: 243-252 (1996)). ⁷Displacement with[³] DPCPX from membranes of CHO cells transfected with human A₁. (See K.N. Klotz, et al. N-S Arch. Pharmacol. 357: 1-9 (1998)) ⁸Inhibition ofCGS 21680-stimulated cAMP in HMC-1 cells. (See I. Feoktistov, and I.Biaggioni, Biochem. Pharmacol. 55: 627-633 (1998)). ⁹Displacement of[125I] APNEA from membranes of CHO cells transfected with rat A3 (see P.J. van Galen, et. al. Mol. Pharmacol. 45: 1101-1111 (1994)).¹⁰Displacement of [125I] ABA from membranes of HEK-293 cells transfectedwith human A3 (see J. A. Auchampach, et al. Mol. Pharmacol. 52: 846-860(1997)). ¹¹Displacement of [3H] NECA from CHO cells transfected withhuman A3 (see K. N. Klotz, et al. N-S. Arch Pharmacol. 357: 1-9 (1998)).

As can be seen from the above table, compounds of formula (I) wherein Ris pyrrolidino have potencies much higher than that of enprofylline, forexample, and are 40- to 60-fold selective compared to A_(2A) and A₁.

All cited patents and publications referred to in this application areherein expressly incorporated by reference.

This invention thus being described, it will be obvious that the samemay be varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the present invention, and allsuch modifications as would be obvious to one of ordinary skill in theart are intended to be included within the scope of the followingclaims.

We claim:
 1. A method of treating diarrhea comprising administering to amammal in need thereof an effective amount of a compound of thefollowing formula:

wherein R is selected from C₁ to C₆ alkyl amine, C₁ to C₆ dialkyl amine,unsubstituted piperidino, piperazino, pyrrolidino, pyrrolino,morpholino, or a pharmaceutically acceptable salt thereof.
 2. A methodof treating inflammatory gastrointestinal tract disorders comprisingadministering to a mammal in need thereof an effective amount of acompound of the following formula:

wherein R is selected from C₁ to C₆ alkyl amine, C₁ to C₆ dialkyl amine,unsubstituted piperidino, piperazino, pyrrolidino, pyrrolino,morpholino, or a pharmaceutically acceptable salt thereof.
 3. A methodof treating depression, comprising administering to a mammal in needthereof an effective amount of a compound of the following formula:

wherein R is selected from C₁ to C₆ alkyl amine, C₁ to C₆ dialkyl amine,unsubstituted piperidino, piperazino, pyrrolidino, pyrrolino,morpholino, or a pharmaceutically acceptable salt thereof.
 4. The methodof claim 1 or 2 or 3, wherein said compound is incorporated with inertcarriers into a tablet and administered orally.
 5. The method of claim 1or 2 or 3, wherein said compound is incorporated with a propellant and asolvent and administered by inhalation of mist.
 6. The method of claim 1or 2 or 3, wherein said compound is incorporated with a pharmaceuticallyacceptable carrier and injected into said mammal.
 7. A compound havingthe following formula:

or a pharmaceutically acceptable salt thereof.
 8. A method of treatingasthma comprising administering to a mammal in need thereof an effectiveamount of a compound of the following formula:

or a pharmaceutically acceptable salt thereof.